PAGEEDITORS: Kyle McKenney, Chloe Suridis, Harrison Kaplan Natland Note:(3/04/14) This group is very behind! Each of you need to post up the relevant parts!
detailed, readable notes
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NOTES:
Chapter 15. Thermodynamics
Caption: This shows an isovolumetric process where heat is added and the volume stays the same so the pressure must go up. (PV =nRT)
Chapter 15. Thermodynamics
Chapter 15. Thermodynamics
Caption: This shows an isobaric process where heat is added and volume varies but the pressure stays the same. (PV=nRT)
Chapter 15. Thermodynamics
Caption: (this lower image is missing stuff you may need to explain....you could take a picture from the text and paste it here instead and it may be better)
Chapter 15. Thermodynamics
Caption:
Heat Engines:
Chapter 15. Thermodynamics
Caption: The engine extracts hear energy (Qh) from a hot reservoir maintained at temperature "Th" converts some of it to useful work, Wnet, and finally expels unused "waste heat" (Qc) into a cold reservoir maintained at temperature "Tc"
The Carnot Cycle
Chapter 15. Thermodynamics
Caption: Maximum efficiency is determined not by any clever engineering but by maximizing the difference between the temperatures of the two reservoirs.
ttp://www.goshen.edu/physix/160/gco/7.1.php
1) The Steam Locomotive Engine:
File:Steam engine (PSF).png
Caption: Two diagrams showing how a steam engine works. Try to see where the energy is flowing from the area of higher temperature to lower temperature.
Where does the steam come from? Caption: "The high-pressure steam for a steam engine comes from a boiler. The boiler's job is to apply heat to water to create steam. There are two approaches: fire tube and water tube. Shown above is a "water-tube boiler" (more common today), in which water runs through a rack of tubes that are positioned in the hot gases from the fire. The following simplified diagram shows you a typical layout for a water-tube boiler.
2) Car Engine: Caption: Images of a standard, 4-cylinder internal combustion engine for a car (the outside, and a sample anatomy of the inside).
Almost all cars currently use what is called a four-stroke combustion cycle to convert gasoline into motion. The four-stroke approach is also known as the Otto cycle, in honor of Nikolaus Otto, who invented it in 1867. The four strokes are illustrated below. They are:
Intake stroke
Compression stroke
Combustion stroke
Exhaust stroke
Art:An internal-combustion engine goes through four strokes: intake, compression, combustion (power), and exhaust. As the piston moves during each stroke, it turns the crankshaft.
The piston is connected to the crankshaft by a connecting rod. As the crankshaft revolves, it has the effect of "resetting the cannon." Here's what happens as the engine goes through its cycle:
The piston starts at the top, the intake valve opens, and the piston moves down to let the engine take in a cylinder-full of air and gasoline. This is the intake stroke. Only the tiniest drop of gasoline needs to be mixed into the air for this to work. (Part 1 of the figure)
Then the piston moves back up to compress this fuel/air mixture. Compression makes the explosion more powerful. (Part 2 of the figure)
When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline. The gasoline charge in the cylinder explodes, driving the piston down. (Part 3 of the figure)
Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe. (Part 4 of the figure)
Now the engine is ready for the next cycle, so it intakes another charge of air and gas.
Caption: Sample images showing an ideal Otto cycle. Note where Q(hot) and Q(cold) come into play.
Computer drawing of Otto cycle with p-V plot.
Caption: Today, most general aviation and private airplanes are powered by internal combustion (IC) engines, much like the engine in a family automobile. Pictured above is the Otto Cycle which is used in all internal combustion engines.
Stage 1 being the beginning of the intake stroke of the engine. The pressure is near atmospheric pressure and the gas volume is at a minimum. Between Stage 1 and Stage 2 the piston is pulled out of the cylinder with the intake valve open. The pressure remains constant, and the gas volume increases as fuel/air mixture is drawn into the cylinder through the intake valve.
Stage 2 begins the compression stroke of the engine with the closing of the intake valve. Between Stage 2 and Stage 3, the piston moves back into the cylinder, the gas volume decreases, and the pressure increases because work is done on the gas by the piston.
Stage 3 is the beginning of the combustion of the fuel/air mixture. The combustion occurs very quickly and the volume remains constant. Heat is released during combustion which increases both the temperature and the pressure, according to the equation of state.
Stage 4 begins the power stroke of the engine. Between Stage 4 and Stage 5, the piston is driven towards the crankshaft, the volume in increased, and the pressure falls as work is done by the gas on the piston.
At Stage 5 the exhaust valve is opened and the residual heat in the gas is exchanged with the surroundings. The volume remains constant and the pressure adjusts back to atmospheric conditions.
Stage 6 begins the exhaust stroke of the engine during which the piston moves back into the cylinder, the volume decreases and the pressure remains constant.
At the end of the exhaust stroke, conditions have returned to Stage 1 and the process repeats itself."
The area enclosed by the cycle on a p-V diagram is proportional to the work produced by the cycle. Pictured above is an ideal Otto cycle in which there is no heat entering (or leaving) the gas during the compression and power strokes, no friction losses, and instantaneous burning occurring at constant volume. In reality, the ideal cycle does not occur and there are many losses associated with each process. These losses are normally accounted for by efficiency factors which multiply and modify the ideal result. For a real cycle, the shape of the p-V diagram is similar to the ideal, but the area (work) is always less than the ideal value.
Caption: Inline format - The cylinders are arranged in a line in a single bank.
Caption:V-style engine (a V6 engine is animated on the left) - The cylinders are arranged in two banks set at an angle to one another. A V8 engine is pictured to the right.
A V-6 cylinder engine
An inline 4 cylinder engine
3) Nuclear Power Plant Caption: A real nuclear power plant....and the one from The Simpsons. What is being expelled from those towers?
Image result for anatomy of a coal fired power plant
Image result for anatomy of a coal fired power plant
Image result for anatomy of a coal fired power plant
6) Natural Gas Power Plant
Image result for natural gas power plant
Image result for natural gas power plant
7) Hydroelectric Power Plant (while we are doing this....)
Image result for anatomy of a hydroelectric dam
Image result for anatomy of a hydroelectric dam
Image result for anatomy of a natural gas power plant
Refrigerators, Heat Pumps and AirConditioners
Vapor-Compression Refrigeration Cycle A working fluid (often called the refrigerant) is pushed through the system and undergoes state changes (from liquid to gas and back). The latent heat of vaporization of the refrigerant is used to transfer large amounts of heat energy, and changes in pressure are used to control when the refrigerant expels or absorbs heat energy.
However, for a refrigeration cycle that has a hot reservoir at around room temperature (or a bit higher) and a cold reservoir that is desired to be at around 34°F, the boiling point of the refrigerant needs to be fairly low. Thus, various fluids have been identified as practical refrigerants. The most common include ammonia, Freon (and other chlorofluorocarbon refrigerants, aka CFCs), and HFC-134a (a non-toxic hydrofluorocarbon).
Stages of the Vapor-Compression Refrigeration Cycle
PV Diagram of the Vapor Compression Refrigeration Cycle
The Vapor-Compression Refrigeration Cycle is comprised of four steps. The conceptual figure of the process shows the PV changes during each part.
Part 1: Compression
In this stage, the refrigerant enters the compressor as a gas under low pressure and having a low temperature. Then, the refrigerant is compressed adiabatically, so the fluid leaves the compressor under high pressure and with a high temperature.
Part 2: Condensation
The high pressure, high temperature gas releases heat energy and condenses inside the "condenser" portion of the system. The condenser is in contact with the hot reservoir of the refrigeration system. (The gas releases heat into the hot reservoir because of the external work added to the gas.) The refrigerant leaves as a high pressure liquid.
Part 3: Throttling
The liquid refrigerant is pushed through a throttling valve, which causes it to expand. As a result, the refrigerant now has low pressure and lower temperature, while still in the liquid phase. (The throttling valve can be either a thin slit or some sort of plug with holes in it. When the refrigerant is forced through the throttle, its pressure is reduced, causing the liquid to expand.)
Part 4: Evaporation
The low pressure, low temperature refrigerant enters the evaporator, which is in contact with the cold reservoir. Because a low pressure is maintained, the refrigerant is able to boil at a low temperature. So, the liquid absorbs heat from the cold reservoir and evaporates. The refrigerant leaves the evaporator as a low temperature, low pressure gas and is taken into the compressor again, back at the beginning of the cycle.
Air conditioner: Caption: This is a sample window-unit air conditioner. Why is half of it sticking outside (shown on the right)? Use the image below to answer this question.
Central-Air-Conditioners.jpg
Caption: These are outdoor air conditioning units. Is the air leaving the fan hot or cold?
Here is an entertaining video that explains the first and second laws of thermodynamics. The air in this colorful hot-air balloon is one example of a thermodynamic system (Source: WileyPlus)
Video Links: First Law of Thermodynamics Khan Academy **Explanation of Carnot Engine** Great explanation of how a carnot engine works. Goes through each stage thoroughly and talks about why they do not exist. Refrigerator, AC, and Heat Pumps Explanation of how refrigerators, ACs, and heat pumps work
Natland Note: (3/04/14) This group is very behind! Each of you need to post up the relevant parts!
NOTES:
Caption: This shows an isovolumetric process where heat is added and the volume stays the same so the pressure must go up. (PV =nRT)
Caption: This shows an isobaric process where heat is added and volume varies but the pressure stays the same. (PV=nRT)
Caption: (this lower image is missing stuff you may need to explain....you could take a picture from the text and paste it here instead and it may be better)
Caption:
Heat Engines:
Caption: The engine extracts hear energy (Qh) from a hot reservoir maintained at temperature "Th" converts some of it to useful work, Wnet, and finally expels unused "waste heat" (Qc) into a cold reservoir maintained at temperature "Tc"
The Carnot Cycle
Caption: Maximum efficiency is determined not by any clever engineering but by maximizing the difference between the temperatures of the two reservoirs.
ttp://www.goshen.edu/physix/160/gco/7.1.php
1) The Steam Locomotive Engine:
Caption: Two diagrams showing how a steam engine works. Try to see where the energy is flowing from the area of higher temperature to lower temperature.
Where does the steam come from?
Caption: "The high-pressure steam for a steam engine comes from a boiler. The boiler's job is to apply heat to water to create steam. There are two approaches: fire tube and water tube. Shown above is a "water-tube boiler" (more common today), in which water runs through a rack of tubes that are positioned in the hot gases from the fire. The following simplified diagram shows you a typical layout for a water-tube boiler.
"Animation of how a steam locomotive's boiler works" (start at 0:30)
http://youtu.be/g8LrAsL4oH0
2) Car Engine:
Caption: Images of a standard, 4-cylinder internal combustion engine for a car (the outside, and a sample anatomy of the inside).
Almost all cars currently use what is called a four-stroke combustion cycle to convert gasoline into motion. The four-stroke approach is also known as the Otto cycle, in honor of Nikolaus Otto, who invented it in 1867. The four strokes are illustrated below. They are:
The piston is connected to the crankshaft by a connecting rod. As the crankshaft revolves, it has the effect of "resetting the cannon." Here's what happens as the engine goes through its cycle:
- The piston starts at the top, the intake valve opens, and the piston moves down to let the engine take in a cylinder-full of air and gasoline. This is the intake stroke. Only the tiniest drop of gasoline needs to be mixed into the air for this to work. (Part 1 of the figure)
- Then the piston moves back up to compress this fuel/air mixture. Compression makes the explosion more powerful. (Part 2 of the figure)
- When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the gasoline. The gasoline charge in the cylinder explodes, driving the piston down. (Part 3 of the figure)
- Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out the tailpipe. (Part 4 of the figure)
Now the engine is ready for the next cycle, so it intakes another charge of air and gas.Caption: Sample images showing an ideal Otto cycle. Note where Q(hot) and Q(cold) come into play.
Caption: Today, most general aviation and private airplanes are powered by internal combustion (IC) engines, much like the engine in a family automobile. Pictured above is the Otto Cycle which is used in all internal combustion engines.
"The graph above shows a p-V diagram of the Otto cycle. Using the engine stage numbering system, we begin at the lower left with:
The area enclosed by the cycle on a p-V diagram is proportional to the work produced by the cycle. Pictured above is an ideal Otto cycle in which there is no heat entering (or leaving) the gas during the compression and power strokes, no friction losses, and instantaneous burning occurring at constant volume. In reality, the ideal cycle does not occur and there are many losses associated with each process. These losses are normally accounted for by efficiency factors which multiply and modify the ideal result. For a real cycle, the shape of the p-V diagram is similar to the ideal, but the area (work) is always less than the ideal value.
Caption: Inline format - The cylinders are arranged in a line in a single bank.
Caption: V-style engine (a V6 engine is animated on the left) - The cylinders are arranged in two banks set at an angle to one another. A V8 engine is pictured to the right.
3) Nuclear Power Plant
Caption: A real nuclear power plant....and the one from The Simpsons. What is being expelled from those towers?
Click here to go inside the workings of a nuclear reactor
video about how a nuclear power plant works
nuclear power plant animation with audio (0:51)
Caption: This animation shows roughly how a nuclear power plant converts water into steam to spin a turbine.
Turkey Point
4) Geothermal Power Plant
Caption: Geothermal power plants use heat from the earth to produce steam, which in turn powers a generator to produce electricity.
ttp://geothermal.marin.org/geopresentation/sld037.htm
http://www.earthlyissues.com/geothermal.htm
5) Coal Fired Power Plant
6) Natural Gas Power Plant
7) Hydroelectric Power Plant (while we are doing this....)
Refrigerators, Heat Pumps and Air Conditioners
Vapor-Compression Refrigeration Cycle
A working fluid (often called the refrigerant) is pushed through the system and undergoes state changes (from liquid to gas and back). The latent heat of vaporization of the refrigerant is used to transfer large amounts of heat energy, and changes in pressure are used to control when the refrigerant expels or absorbs heat energy.
However, for a refrigeration cycle that has a hot reservoir at around room temperature (or a bit higher) and a cold reservoir that is desired to be at around 34°F, the boiling point of the refrigerant needs to be fairly low. Thus, various fluids have been identified as practical refrigerants. The most common include ammonia, Freon (and other chlorofluorocarbon refrigerants, aka CFCs), and HFC-134a (a non-toxic hydrofluorocarbon).
Stages of the Vapor-Compression Refrigeration Cycle
The Vapor-Compression Refrigeration Cycle is comprised of four steps. The conceptual figure of the process shows the PV changes during each part.
Air conditioner:
Caption: This is a sample window-unit air conditioner. Why is half of it sticking outside (shown on the right)? Use the image below to answer this question.
Caption: These are outdoor air conditioning units. Is the air leaving the fan hot or cold?
Here is an entertaining video that explains the first and second laws of thermodynamics.
The air in this colorful hot-air balloon is one example of a thermodynamic system (Source: WileyPlus)
Video Links:
First Law of Thermodynamics Khan Academy
**Explanation of Carnot Engine** Great explanation of how a carnot engine works. Goes through each stage thoroughly and talks about why they do not exist.
Refrigerator, AC, and Heat Pumps Explanation of how refrigerators, ACs, and heat pumps work
SAMPLE PROBLEMS:
WEBSITES:
http://science.howstuffworks.com/transport/engines-equipment/steam1.htm
(Great animation showing how a steam engine works!)
SOURCES:
http://commons.wikimedia.org/wiki/File:Steam_engine_(PSF).png
(image of steam engine)
http://auto.howstuffworks.com/engine.htm/printable
(text and images of car engine)
http://ffden-2.phys.uaf.edu/212_spring2007.web.dir/sedona_price/phys_212_webproj_refrigerators.html
(refrigerator cycle info and diagram)
http://www.45nuclearplants.com/nuclear_reactor_designs.asp
(nuclear power info)
http://www.grc.nasa.gov/WWW/k-12/airplane/thermo.html
(four pictures about thermodynamics)